Acute heat tolerance of cardiac excitation in the brown trout (Salmo trutta fario)
Acute heat tolerance of cardiac excitation in the brown trout (Salmo trutta fario)
复制标题
褐鳟心脏兴奋的急性耐热性（Salmo trutta fario）
DOI：
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发表时间：
2014
影响因子：
2.8
通讯作者：
S. Egginton
中科院分区：
文献类型：
--
作者：
M. Vornanen;J. Haverinen;S. Egginton
研究了褐鳟鱼（萨尔莫trutta fario）的热耐受上限和热诱导心力衰竭的机制。通过急性温度升高确定体外离子通道功能和窦房收缩性以及体内心电图（ECG）开始失效的点（断点温度，BPT）。一般而言，心脏的电兴奋在完整动物中对热最敏感（心电图，ECG），在分离的心肌细胞中最不敏感（离子电流）。心肌细胞Ca ~（2+）和K ~+电流的BPT（>28°C）明显高于在体心率的BPT（23.5±0.6°C）（P<0.05）。肌膜离子电导中的一个显著例外是Na+电流（INa），它是最热敏的分子功能，BPT为20.9±0.5°C。INa的耐热性低，表现为动作电位上升速率（21.7±1.2°C）和脉冲传递速度（21.9±2.2°C）的BPT较低。这些来自不同生物组织水平的发现强烈表明，Na+通道功能的热依赖性恶化扰乱了电兴奋在心脏上的正常传播，导致心脏节律性的进行性变异（漏跳、快速跳动的爆发）、心率降低并最终停止正常心跳。在心脏离子电流INa是“最薄弱的环节”，并可能是一个限制因素的上限热耐受性的电刺激在褐鳟鱼的心脏。INa的热敏性可能是由于Na+通道的非常高的通量速率和快速门控动力学的功能要求，即高催化活性和热稳定性之间的权衡。
The upper thermal tolerance and mechanisms of heat-induced cardiac failure in the brown trout (Salmo trutta fario) was examined. The point above which ion channel function and sinoatrial contractility in vitro, and electrocardiogram (ECG) in vivo, started to fail (break point temperature, BPT) was determined by acute temperature increases. In general, electrical excitation of the heart was most sensitive to heat in the intact animal (electrocardiogram, ECG) and least sensitive in isolated cardiac myocytes (ion currents). BPTs of Ca2+ and K+ currents of cardiac myocytes were much higher (>28°C) than BPT of in vivo heart rate (23.5±0.6°C) (P<0.05). A striking exception among sarcolemmal ion conductances was the Na+ current (INa), which was the most heat-sensitive molecular function, with a BPT of 20.9±0.5°C. The low heat tolerance of INa was reflected as a low BPT for the rate of action potential upstroke in vitro (21.7±1.2°C) and the velocity of impulse transmission in vivo (21.9±2.2°C). These findings from different levels of biological organization strongly suggest that heat-dependent deterioration of Na+ channel function disturbs normal spread of electrical excitation over the heart, leading to progressive variability of cardiac rhythmicity (missed beats, bursts of fast beating), reduction of heart rate and finally cessation of the normal heartbeat. Among the cardiac ion currents INa is ‘the weakest link’ and possibly a limiting factor for upper thermal tolerance of electrical excitation in the brown trout heart. Heat sensitivity of INa may result from functional requirements for very high flux rates and fast gating kinetics of the Na+ channels, i.e. a trade-off between high catalytic activity and thermal stability.
热带和温带鱿鱼轴突传播动作电位的比较：不同的持续时间和传导速度与离子电导水平相关。
DOI：
10.1242/jeb.205.12.1819
发表时间：
2002
期刊：
The Journal of experimental biology
影响因子：
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作者：
Rosenthal,JoshuaJC;Bezanilla,Francisco
通讯作者：
Bezanilla,Francisco
DOI：
10.1152/ajpheart.1998.274.6.h1902
发表时间：
1998-06-01
影响因子：
4.8
作者：
Golod, DA;Kumar, R;Joyner, RW
通讯作者：
Joyner, RW